Linear function is the most basic function in junior high school mathematics, which is divided into the form of passing the origin and the form of not passing the origin. The linear function passing through the origin means that the function passes through the origin when it passes through one, three or two or four quadrants, but the function of the origin means that the image of the linear function passes through three quadrants.

The figure shows a linear function image and its properties:

Note: When doing function type questions, students should master the drawing steps of a function skillfully:

1, list (usually find 4-6 points);

2, tracing points;

3, connection, you can do a function mirror. (Connected by a smooth straight line)

02

quadratic function

Quadratic function is a learning function based on linear function. The basic expression of quadratic function is y=ax? +bx+c(a≠0). This also means that the highest degree of a quadratic function must be quadratic.

The image of a quadratic function is a parabola, and its symmetry axis is parallel or coincident with the Y axis. The definition of quadratic function is quadratic polynomial (or monomial).

The picture shows the quadratic function image:

When learning quadratic function, students should master the image shape and properties of quadratic function skillfully. The common solution of quadratic function is the combination of numbers and shapes.

When solving quadratic function problems, students should learn to solve quadratic function problems by combining numbers with shapes. The so-called combination of numbers and shapes is to draw the image of the function through the function equation and the conditions given in the problem, and analyze what the problem requires according to the image. This solution is more intuitive.

03

inverse proportion function

Inverse proportional function is a difficult part in junior high school mathematics function. When students do this kind of problems, they often lose points because of negligence.

Inverse proportional function diagram:

Inverse proportional function means that the left side of the equation is the function y, and the right side of the equal sign is a fraction of the molecule k, where k is not zero. At the same time, k is also called the proportional coefficient. X and y can take all non-zero real numbers.

When doing inverse proportional function, the easiest way is to draw a picture, and then solve the problem according to the graphic function, so the key to solving the problem is to draw a picture.

Junior high school mathematics mainly involves these three functions. Students should practice frequently and master the similarities of each question. At the same time, you should practice drawing more when you are doing problems, and form good habits.